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Test ID: HCQ Hydroxychloroquine, Serum

Useful For

Monitoring serum hydroxychloroquine concentrations, assessing compliance, and adjusting dosage in patients

Method Name

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Reporting Name

Hydroxychloroquine, S

Specimen Type

Serum Red

Specimen Required

Collection Container/Tube: Red top (gel tubes/SST are not acceptable)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Collect specimen immediately before next scheduled dose.

2. Centrifuge and aliquot serum into plastic vial within 2 hours of collection.

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Red Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  21 days

Clinical Information

Hydroxychloroquine is an antimalarial drug used to treat or prevent malaria. It is highly effective against erythrocytic forms of Plasmodium but not effective against exoerythrocytic forms of parasites. Hydroxychloroquine is also used to treat symptoms of acute or chronic rheumatoid arthritis and systemic lupus erythematosus (SLE).


Adult doses range from 400 mg/week for suppressive therapy to 1200 mg/day for acute malaria attacks. Typical daily doses of 200 to 600 mg are used for SLE and rheumatoid diseases. Hydroxychloroquine has a long terminal elimination half-life in blood (>40 days), which exceed those in serum. The oral bioavailability averages 75%.


Hydroxychloroquine accumulates in several organs, especially melanin-containing retina and skin. Mild to moderate overdose can result in gastrointestinal tract effects (ie, nausea, vomiting, and abdominal pain), headache, visual and hearing disturbances, and neuromuscular excitability. Acute hepatitis, cardiotoxicity, and retinopathy may occur with therapeutic doses. The effects of overdosage with hydroxychloroquine include headache, drowsiness, visual disturbances, convulsions, cardiovascular collapse, and respiratory arrest. Toxic retinopathy has also been associated with higher doses and longer duration of use.

Reference Values

For suppressive treatment of malaria, suggested plasma or serum concentrations should be >10 ng/mL.


For systemic lupus erythematosus, proposed serum target concentrations should be ≥500 ng/mL.


The serum concentration should be interpreted in the context of the patient's clinical response and may provide useful information in patients showing poor response, noncompliance, or adverse effects. Concentrations less than 106 ng/mL have been associated with non-compliance.

Clinical Reference

1. McChesney EW BW, McAuliff JP: Laboratory studies on the 4-aminoquinoline antimalarials: II. Plasma levels of chloroquine and hydroxychloroquine in man after various oral dosage regimens. Antibiot Chemother (Northfield). 1962;12:583-594

2. Mok CC, Penn HJ, Chan KL, Tse SM, Langman LJ, Jannetto PJ. Hydroxychloroquine serum concentrations and flares of systemic lupus erythematosus: A longitudinal cohort analysis. Arthritis Care Res. 2016 Sep;68(9):1295-1302. doi: 10.1002/acr.22837

3. Durcan L, Clarke WA, Magder LS, Petri M: Hydroxychloroquine blood levels in systemic lupus erythematosus: clarifying dosing controversies and improving adherence. J Rheumatol. 2015 Nov;42(11):2092-2097. doi: 10.3899/jrheum.150379

4. Blanchet B, Jallouli M, Allard M, et al: SATO188 Whole blood versus serum hydroxychloroquine levels for drug monitoring of patients with systemic lupus erythematosus: preliminary results of a pharmacological study. Ann Rheum Dis. 2019;78(2):1168-1169

5. Soichot M, Megarbane B, Houze P, et al: Development, validation and clinical application of a LC-MS/MS method for the simultaneous quantification of hydroxychloroquine and its active metabolites in human whole blood. J Pharm Biomed Anal. 2014 Nov;100:131-137. doi: 10.1016/j.jpba.2014.07.009

6. Wang LZ, Ong RYL, Chin TM, et al: Method development and validation for rapid quantification of hydroxychloroquine in human blood using liquid chromatography-tandem mass spectrometry. J Pharm Biomed Anal. 2012 Mar 5;61:86-92. doi: 10.1016/j.jpba.2011.11.034

7. Disposition of Toxic Drugs and Chemicals in Man. 10th ed. Biomedical Publications; 2014

8. Tett SE, Cutler DJ, Day RO, Brown KF: A dose-ranging study of the pharmacokinetics of hydroxy-chloroquine following intravenous administration to healthy volunteers. Brit J Clin Pharmacol. 1988 Sep;26(3):303-313

9. Gautret P, Lagier JC, Parola P, et al: Hydroxychloroquine and azithromycin as a treatment of COVID-19: results of an open-label non-randomized clinical trial. Int J Antimicrob Agents. 2020 Jul;56(1):105949. doi: 10.1016/j.ijantimicag.2020.105949

10. Kim SH: Comparison of lopinavir/ritonavir or hydroxychloroquine in patients with mild coronavirus disease (COVID-19). US National Library of Medicine (NLM). 2020. Accessed 03/2020. Available at

11. Lu H: Efficacy and safety of hydroxychloroquine for treatment of pneumonia caused by 2019-nCoV (HC-nCoV). US National Library of Medicine (NLM). 2020. Accessed March 11, 2022. Available at

12. Post-exposure prophylaxis for SARS-coronavirus-2. US National Library of Medicine (NLM). 2020. Accessed March 11, 2022. Available at

Report Available

3 to 7 days

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
HCQ Hydroxychloroquine, S 3684-8


Result ID Test Result Name Result LOINC Value
64947 Hydroxychloroquine, S 3684-8

Day(s) Performed

Sunday, Tuesday, Thursday


If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.

Mayo Clinic Laboratories | Microbiology and Infectious Disease Catalog Additional Information: